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Glossary

A glossary of science-related words.

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Glossary terms A–Z definitions

E. coli (Escherichia coli)

A bacterium commonly found in the gut of warm-blooded organisms that can cause serious infections.
Alternative glossary terms: E. coli, Escherichia coli

earthenware

A common pottery material used to make tableware and decorative objects.

earthworm cast

The digested material that earthworms excrete back into the soil.

echinoderm

A type of marine invertebrate such as starfish and sea urchins that has a radial symmetry. Most often, the body consists of five equal segments.

echo-sounder

An echo-sounder is a device for measuring and mapping the depth of water between the underneath of a boat or ship and another object; usually it is used to determine where a seabed or lakebed is. It works by sending a pulse or 'ping' of sound down and measuring the time taken for the echo (reflected sound wave) from the object to come back. It can be adjusted to bounce off objects such as fish populations.

ecological community

A group of different species that live in one location and interact with each other.

ecologist

A scientist who studies ecology – the relationships between living things and their environment.

ecology

The study of the interactions of living organisms with each other and their environment.

ecophysiology

The study of an organism’s physiology in relation to its environment.

ecosystem

An interacting system made up of animals, plants and/or microorganisms as well as the physical and chemical environment they live in.

ecosystem services

The benefits ecosystems provide for the environment and people. These include services such as nutrient cycling, flood control, provision of food and water and aesthetic and cultural experiences.

ectotherm

An animal whose body temperature is regulated by the surrounding temperature.

effluent

The outflowing of water from a system – often refers to the discharge of sewage, but can also be natural, for example, the outflowing of a river to the sea. Agricultural effluent refers to the treated and untreated wastewater collected during the management of livestock.

effusion

A process that involves gas molecules escaping through a small hole in a containing vessel. It explains why inflated toy balloons deflate when left alone for several days.

egestion

Removal of undigested food or faeces from the large intestine.

elasticity

The ability of a solid to return to its original shape or form after it has been stretched or compressed.

electric charge

An excess of electrons on an object gives it a negative charge whereas a deficiency of electrons gives it a positive charge. Protons carry a positive charge and electrons carry a negative charge. Ions carry a positive or negative charge.

electric field

Any region where a charged object experiences an electric force.

electrical circuit

It is made up of a power source, other electrical components and an unbroken pathway along which an electric current exists or is able to pass.

electrical resistance

For a given object, it is a measure of the opposition to the passage of electric current.

electricity

A general term that includes a variety of phenomena resulting from the presence and flow of electrical charge.

electrocatalyst

A substance that increases the rate of a chemical reaction that makes or uses electricity.

electrode

Terminal where electricity goes in or out of a conductor, for example, the positive and negative terminals of a battery.

electroencephalogram (EEG)

The measurement and recording of the electrical activity of the brain, usually done by placing electrodes on the brain. It can be used to look at brain activity and to diagnose brain tumours. EEG is used as the abbreviation for electroencephalography (the process), electroencephalograph (the instrument) and electroencephalogram (the recording).

electrolysis

A chemical change caused by passing electricity through a solution.

electromagnetic spectrum

The complete range of electromagnetic radiation from the shortest waves (gamma rays) to the longest (radio waves).

electron

A light subatomic particle with negative charge, found in the space surrounding an atomic nucleus.

electron microprobe

An instrument used to measure very small quantities of minerals contained in rock samples.

electron microscope

A microscope that uses a focused beam of electrons, rather than visible light, to magnify objects. Electron microscopes use electromagnetic coils to focus the electron beam (instead of the glass lenses used to focus light in optical microscopes).

electronic chip

A tiny slice of semiconductor material, such as silicon, processed to form a type of integrated circuit or component such as a transistor.

electronics

The study of the behaviour and control of electrons. This field has expanded enormously with the discovery of semiconductors.

electrophoresis

When an electrical current is applied to a solution to separate out different sized particles, the most common use being DNA gel electrophoresis where DNA in a gel matrix are separated.

electrostatic forces

The forces that occur between electrically charged objects.

element

An element is a substance made of atoms all with the same atomic number. Elements cannot be split into simpler substances using normal chemical methods.

elite athlete

One of the top few in their sport.

ellagic acid

A phytochemical, or plant chemical, found in raspberries, strawberries, cranberries, walnuts, pecans, pomegranates and other plant foods. Ellagic acid is said to have antioxidant, antimutagen and anticancer properties.

elvers

Juvenile eels.

embryo

The product of a fertilised egg, from the zygote until the foetal stage.

empirical

Based on observation.

endangered

A species that is possibly going to become extinct soon due to limited numbers of individuals alive or not enough habitat to live in.

endemic

Native to only one location. Species endemic to New Zealand naturally occur only in New Zealand but may have been introduced elsewhere in the world.

endocrine

Secreting a chemical substance directly into the bloodstream or tissue fluid rather than into a duct.

endogeic

Greek for ‘within the Earth’. Earthworms occupying the endogeic niche live in the top 20 centimetres of soil.

endometrial

Of or belonging to the endometrium – the mucous membrane lining the uterus.

endophyte

An organism, often a bacterium or fungus, living inside a plant.

endothermic

An animal’s ability to maintain constant body temperature in different surrounding temperatures.

endurance

Ability of a muscle to produce force continually over a period of time.

energy dispersive X-ray analysis

Also known as EDXA, this is a technique used to determine the individual elements of an object. An electron beam is passed over the sample, which causes X-rays to be emitted from the sample. The energy of the X-rays emitted varies with different elements, which enables scientists to obtain an image of each element in the sample. As X-rays are of low intensity, this process can take several hours.

energy prospecting

Using computer models to find areas where the wind strength and consistency is suitable for harnessing wind energy.

enteric nervous system

The digestive system’s own local nervous system that can and does function autonomously but normally works in association with the central nervous system.

entomologist

A scientist who studies insects.

entrainment

To draw in and transport by the flow of a fluid.

enzymatic hydrolysis

A chemical process in digestion in which bonds holding the structural units of macromolecules together are broken with the involvement of an enzyme and water molecules.

enzyme

A complex protein that acts as a catalyst in specific biochemical reactions. For example, saliva contains an enzyme called amylase that can break down starch into simple sugars.

Eocene

The second geological epoch (a division of time by which geological periods are divided) of the Tertiary period, 56.5–35.5 million years ago, when early forms of mammals were evolving following the extinction of dinosaurs.

eon

The longest division of geologic time consisting of two or more eras. For example, the Phanerozoic eon consists of three eras – the Paleozoic, Mesozoic and Cenozoic.

epicentre

The point on the Earth’s surface directly above the focus of the earthquake.

epidemic

A disease or health-related issue that shows up in more cases than would normally be expected.

epidemiology

The branch of medical science that deals with the study (including type, origin and geographical spread) and control of diseases in a population – literally, the study of epidemics.

epidermis

The surface layer of the two main layers that make up the skin. Contains basal cells, squamous cells and melanocytes.

epigeic

Greek for ‘upon the Earth’. Earthworms occupying the epigeic niche live at or near the soil surface.

epigenetics

The study of the mechanisms that can make changes in gene function without making changes in the underlying DNA sequence of the gene.

epigenomics

The study of the overall state of epigenes in a cell. One genome can give rise to many epigenomes as different genes are activated or deactivated.

epithelial

Cells that line the cavities and surfaces of structures throughout the body. The outermost layer of our skin is made from dead squamous epithelial cells.

epoch

A division of geologic time less than a period but greater than an age.

equilibrium

The situation when the forces and torques acting on a part of the body are balanced.

era

A major division of geologic time that is usually divided into two or more periods. For example, the Cenozoic era consists of three periods – the Paleogene, Neogene and Quaternary.

eradication

The deliberate local extinction of an introduced species as part of pest control.

erosion

Wearing away of the land by mechanical action, such as by wind, water and glaciers, and by material carried in them. It can also be the gradual wearing away of a surface due to friction, particle collisions or chemical attack. Part of the process of erosion transports material away.

error

The difference between the measured result and the accepted value is the error in the result.

  • error = measured value - accepted value
  • % error = (error in measurement/accepted value) x 100
estuary

A partially enclosed body of water where freshwater mixes with saltwater from the sea.

ethanol

A volatile, flammable, colourless liquid. It is also known as ethyl alcohol or pure alcohol.

eukaryote

A group of organisms whose cells contain cell organelles such as a nucleus, chloroplast or mitochondria. This group includes fungi, plants and animals.

euthanasia

The practice of ending a life in a manner that relieves pain and suffering.

eutrophication

A process where waterways, lakes and shallow sea areas receive excess nutrients that stimulate excessive plant or algae growth. This excessive growth depletes the available oxygen in the water and causes other organisms to die off.

evaporation

The process by which a liquid is converted into a gas, without necessarily reaching the boiling point.

evaporative cooling

A reduction in temperature due to the evaporation of a liquid, such as water, from a surface. The temperature reduction depends upon the magnitude of the latent heat of vaporisation of the liquid concerned.

evidence

Data that is considered reliable and valid.

evolution

In biology, the change in the genetic material and/or the behaviour of a population of organisms over time.

exclusive economic zone (EEZ)

A seazone prescribed by the United Nations Convention on the Law of the Sea over which a country has special rights concerning the exploration and use of marine resources. It extends 200 nautical miles (370 kilometres) from the coast.

exocrine

Secreting a chemical substance that is transported by a duct out to a particular region of the body.

exoskeleton

A hard structure that develops on the outside of an invertebrate animal, giving it both protection and support.

extant

Organisms that exist or live at the present time. Extant is the opposite of extinct.

extension

When a part of the body - muscle and joint - is in a non-flexed position.

extensor

A muscle that bends a part of the body outwards.

extinction

In biology, the death of the last remaining individual of a species.

extrasolar planet

Planets that orbit stars outside our own Solar System. Also called exoplanets.

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